Ace:Prototype Witness Validation

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1. From the CSI Registry, the Post & Validate gathers the CSI values that share the same Time Frame ID, and builds an authentication tree using the same technique that produced the original witness. The root of the authentication tree is concatenated with the previous witness, which is saved from the previous witness validation process. This concatenated value is hashed to generate a validation witness.
2. The Post & Validate retrieves the published witness of this Time Frame ID from the Internet. The published witness is then compared to the validation witness. The validation fails if the two witnesses are different, in which case all the CSI values within this Time Frame ID are marked invalid.

Once CSI is marked invalid, the audit on the digital objects that belong to the CSI will fail, in which case ACE will forward its alert message to the archive administrator who will then take the appropriate steps. For example, the archive administrators can simply re-register the digital objects to ACE.